The present invention generally relates to cellular mobile radio systems based upon the so called GSM standard (GSM--Global System for Mobile communication) and more particularly to a method of managing supplementary service procedures.
A GSM network basically comprises at least one base station system BSS including a base station controller BSC and base station transceivers BTS. The GSM network furthermore includes a mobile services switching centre MSC, a home location register HLR and a visitors location register VLR.
Each subscribing mobile station MS belongs to a HLR in a home network, wherein permanent subscriber data is stored. When a mobile station is registered in a MSC/VLR as a new visitor, that mobile station's HLR sends a copy of the relevant subscriber data to MSC/VLR.
Supplementary service procedures are those procedures that are used by an MS (Mobile Station) in the GSM-system either to change supplementary service data or to question the network about current supplementary service data. This procedure may, for instance, involve activating a supplementary service, registering data for a supplementary service, inquiring about data for a given supplementary service, etc.
In a GSM-network, subscriber data is stored permanently in HLR as indicated above. This implies that procedures used by an MS to request changes in subscriber service data will preferably be terminated in HLR, which is responsible for such data. The MSC/VLR responsible for signalling with MS store only copies of the supplementary service data. This data is received in MSC/VLR from HLR in conjunction with a report from MS that the mobile is a new "visitor" in MSC/VLR.
Since it is MSC/VLR that communicates directly with MS in conjunction with supplementary service procedures, it is MSC/VLR that terminates these procedures as seen from MSC. However, as mentioned, the GSM-network is distributed so that, in the main, it is the HLR which is the actual recipient or target of these procedures. MSC/VLR merely constitutes a procedure transfer point. This is an exception rather than a rule however, since certain procedures are terminated in MSC/VLR and not all of the procedures are transferred to HLR. An example in this respect is found in a query which concerns data that is applicable at that time for a given supplementary service, this query being terminated in MSC/VLR and not in HLR. This applies, however, only to those services that are controlled by MSC/VLR. When signalling between MS and MSC/VLR, the supplementary service procedures are implemented purely in protocol fashion with the aid of rules that are in accord with the ROSE-concept (Remote Operations Service Element--specified in CCITT X.219 and X.220). This means that all procedures are specified in a protocol fashion as operations. These operations are descriptions of the configuration of the forward and backward messages included in the actual procedure from the aspect of their protocol content. The forward and backward messages included in an operation are called components.
CCITT #7 TCAP (Translation Capabilities Application Part--specified in CCITT Q.771-Q.775) is utilized when signalling between MSC/VLR and HLR. TCAP is also based on ROSE. This enables operations that are used in signalling between MSC/VLR and MS to be "imported" and used also when signalling between MSC/VLR and HLR.
EP 295,678 describes a radio telephony system in which a "radio connector" sends an ID-number for the radio zone in which it is located. The radio telephone compares the received radio-zone ID-number with the number stored in a memory. If the ID-numbers do not mutually coincide, the radio-telephone ID-number and the received radio-zone ID-number are sent as a position entry signal to a radio control unit, via a "radio connector". The radio-channel control unit registers the two ID-numbers.
U.S. Pat. No. 4,901,340 discloses essentially a general picture of the standpoint of techniques with regard to mobile telephony, where mobiles are located in foreign areas outside their home service area.